Memory is one of the most important capabilities of our mind since it determines our individuality. Memory formation involves different stages: acquisition, consolidation and retrieval. There are many studies about early stages, however little is known about memory retrieval. Retrieval is the use of learned information and represents a big problem in patients with memory deficits where the main issue is that they can learn but cannot remember. Previous findings have demonstrated that 5-hydroxytryptamine (5-HT) is a neurotransmitter involved in memory process. Hence, here we are exploring the role of 5-HT in memory retrieval by using its metabolic precursor l-tryptophan and several ligands at 5-HT_1A and 5-HT₇ receptors. Experimental protocol consisted of evaluating conditioned responses (%CR) after one week of interruption following autoshaping sessions for memory formation; a decrease of %CR was interpreted as memory decay. Systemic administration of: (1) l-tryptophan (50 and 100 mg/kg), (2) 5-HT_1A receptor agonist 8-OH-DPAT (0.031 and 0.062 mg/kg), (3) the selective antagonist 5-HT_1A receptor WAY 100635 (0.3 and 0.6 mg/kg), (4) the 5-HT₇ receptor agonist, LP 211, in a dose-dependent manner (1, 2.5, 5.0 and 10.0 mg/kg) enhanced memory retrieval. Further, the 5-HT₇ receptor antagonist, SB 269970 (10.0 mg/kg), had no effect. Finally, SB 269970 (10.0 mg/kg) significantly blocked memory retrieval enhancement produced by 10.0 mg/kg LP 211, but not that induced by 2.5 mg/kg LP 211.These results, taken together, suggest that activation of 5-HT_1A and 5-HT₇ receptors enhanced memory retrieval and these receptors may be therapeutic targets to improve long-term memory retrieval.

记忆是我们头脑中最重要的能力之一，因为它决定了我们的个性。记忆的形成涉及不同的阶段：获得、巩固和提取。有许多关于早期阶段的研究，但对记忆检索知之甚少。检索是对所学信息的使用，它代表了记忆缺陷患者的一个大问题，其中主要问题是他们可以学习但无法记住。先前的研究结果表明，5-羟色胺 (5-HT) 是一种参与记忆过程的神经递质。因此，我们在这里通过使用其代谢前体l-色氨酸和 5-HT _1A和 5-HT _{7 的}几种配体来探索 5-HT 在记忆恢复中的作用受体。实验方案包括在记忆形成的自动整形会话后中断一周后评估条件反应 (%CR)；%CR 的降低被解释为记忆衰退。全身给药：(1) l-色氨酸 (50 和 100 mg/kg)，(2) 5-HT _1A受体激动剂 8-OH-DPAT (0.031 和 0.062 mg/kg)，(3) 选择性拮抗剂 5- HT _1A受体 WAY 100635（0.3 和 0.6 毫克/千克），（4）5-HT ₇受体激动剂 LP 211，以剂量依赖性方式（1、2.5、5.0 和 10.0 毫克/千克）增强记忆检索。此外，5-HT ₇受体拮抗剂 SB 269970 (10.0 mg/kg) 没有效果。最后，SB 269970 (10.0 mg/kg) 显着阻断了 10.0 mg/kg LP 211 产生的记忆恢复增强，但不是由 2.5 mg/kg LP 211 诱导的。这些结果综合起来表明 5-HT _{1A 的}激活和 5-HT ₇受体增强记忆检索，这些受体可能是改善长期记忆检索的治疗靶点。